The present application relates to a lateral heterojunction bipolar transistor (HBT) structure, and particularly to a lateral HBT including an epitaxially grown intrinsic base and a deposited extrinsic base that is self-aligned with the intrinsic base and methods of manufacturing the same.
Heterojunction bipolar transistors (HBTs) include a heterojunction, i.e., a junction of two semiconductor materials having different band gaps, which coincides with a p-n junction between the base and the emitter. The wider bandgap of the emitter relative to the bandgap of the base in an HBT increases the current gain relative to a bipolar junction transistor employing a same semiconductor material across the base and the emitter and having similar physical dimensions and doping profiles for the base and emitter.
Heterojunction bipolar transistors (HBTs) known in the art include a pair of heterojunctions, i.e., junctions of two semiconductor materials having different bandgaps, which coincide with p-n junctions between the base and the emitter/collector. The wider bandgap of the emitter relative to the bandgap of the base in an HBT increases the current gain relative to a bipolar junction transistor employing a same semiconductor material across the base and the emitter and having similar physical dimensions and doping profiles for the base and emitter.
However, there can be difficulties associated with the manufacturing of the HBTs and with the functioning of HBTs. For instance, and in the conventional art, the base is formed first which, in turn, may require additional patterning (e.g., lithography and reactive ion etching (RIE)) in order to enable deposition or epitaxial growth of the emitter/collector material to form an HBT having an emitter/collector including materials with a wider bandgap than that for an intrinsic base, thereby resulting in a more complicated process for forming the HBT. Moreover, the thermal cycles involved in formation of emitter/collector could compromise the integration of the intrinsic base. Therefore, there remains a need to develop a method that can simplify the fabrication and improve the device performance of the HBTs.